beneath the table to the abstract. Use the Word Count cmd under Utilites menu for counting Significance HIV transmission to infants by breast feeding after maternal anti-HIV antibodies decline is well documented. Neonatal vaccination may reduce HIV transmission to children in developing nations where safe alternatives to breast feeding are not available. However, a neonatal anti-HIV vaccine must elicit immunity in the presence of maternal HIV antibodies. Objectives Infection of newborn rhesus macaques with simian immunodeficiency virus is a well-established model for pediatric HIV infection and AIDS. This pilot study evaluated whether proviral DNA from virulence-attenuated SHIV-33 (DNA from a molecular clone consisting of the HIV-1 SF-33 envelope gene in an otherwise SIV genome) could (1) establish infection in neonates with maternal SIV antibodies, and (2) provide protection against oral SIV one year after SHIV inoculation. Results Three rhesus macaques were immunized during pregnancy with whole-inactivated SIV in adjuvant and transferred high titer SIV-specific serum antibodies to their infants. Four neonates with no anti-SIV antibodies served as controls. All seven infants were inoculated intramuscularly with 100 ug of SHIV-33 proviral DNA within 3 days of birth. Five of the seven infants became infected with SHIV-33 two infants with anti-SIV antibodies and three infants with no SIV antibodies. Thus, maternal anti-SIV antibodies did not prevent replication of SHIV-33 in neonates after DNA vaccination. At one year of age DNA vaccinated animals and 4 naove rhesus were challenged orally with pathogenic SIVmac239. All animals became infected after challenge. Only vaccinated animals had low viremia and no disease; unvaccinated controls had persistent, high viremia and 2 animals died with AIDS by 6 months after challenge. These results suggest that plasmid DNA encoding attenuated HIV might be devel oped as a vaccine to protect infants against HIV in breast milk. Future Directions Determine whether DNA vaccination of rhesus newborns can protect against oral SIV as early as one month of age. KEY WORDS pediatric simian AIDS, oral SIV transmission, perinatal HIV transmission, neonatal immunization, live-attenuated vaccine FUNDING NIH Grants RR00169 and AI039109, E. Glaser Pediatric AIDS Foundation Scientist Award 8-97